Stringed musical instrument with resonant diaphragm



July 29, 1969 w, sNlDER 3,457,820

STRINGED MUSICAL IN STRUMENT WITH RESONANT DIAPHRAGM Filed June 22, 1967 2 Sheets-Sheet l INVENTOR. 1M HARTFORD JN I DER ad/M0 Arrows 5x July 29, 1969 w. H. SNIDER' 3,457,820

STRINGED MUSICAL INSTRUMENT WI'Il-I RESONAN'I DIAPHRAGM Filed June 22. 1967 2 Sheets-Sheet 2 I04 /05 INVENTORY 2/10 66 W. HA 471 020 J/vmm m 372 15; MM

AT TO RN EY United States Patent U.S. Cl. 84-296 15 Claims ABSTRACT OF THE DISCLOSURE A banjo or guitar type stringed instrument having a peg head and neck connected to a frame having a string anchor, the frame having sufficient strength to withstand the tension forces in the strings and in a diaphragm; the frame defining an opening with a lineal fixed abutment at one end and a parallel adjustable abutment at the other end; a sheet of flexible material stretched taut between the abutments and underneath strings stretched between the peg head and anchor; and a bridge supported on an intermediate portion of the diaphragm, and in turn suporting the strings intermediate of their length.

A modified instrument has a body like a guitar with fixed and adjustable abutments supporting a taut diaphragm in spaced relation between the strings and the top of the guitar body. A first bridge supports the strings from the diaphragm; and a second adjustable bridge is arranged to be selectively positioned in spaced relation to the diaphragm, or in supporting relation between the top of the guitar body and the underside of the diaphragm under the first bridge.

Outline of invention The cost of a banjo-like instrument is reduced by stretching a rectangular flexible diaphragm in one direction only within an opening formed by the frame of the body. The strings are supported by a bridge on the diaphragm and produce the sound of a banjo by imparting string vibrations to the taut diaphragm.

As a refinement, the one-way stretched diaphragm is mounted on the hollow resonating body of a guitar to combine the diaphragm vibrating tones with the hollow body resonating tones for an improved banjo-like tone and instrument. Alternatively, a second bridge may support the first bridge from the top of the hollow body to reduce or eliminate the vibrating diaphragm tones and produce a guitar-like tone from the same instrument.

The drawings, of which there are two sheets, illustrate a preferred form of the banjo-like sounding instrument; and a preferred form of instrument convertible to produce banjo-like tones or guitar-like tones.

FIGURE 1 is a top plan view of a banjo-like instrument embodying the invention.

FIGURE 2 is an enlarged, fragmentary cross sectional view along the plane of the line 2-2 in FIGURE 1.

FIGURE 3 is an enlarged fragmentary cross sectional view along the plane of the line 3-3 in FIGURE 2.

FIGURE 4 is an enlarged fragmentary cross sectional view along the plane of the line 44 in FIGURE 3.

FIGURE 5 is a top plan view of a guitar type form of the instrument.

FIGURE 6 is an enlarged, fragmentary, cross sectional view along the plane of the line 6-6 in FIGURE 5.

FIGURE 7 is an enlarged, fragmentary, cross sectional view along the plane of the line 77 in FIGURE 6.

FIGURE 8 is an enlarged, fragmentary, cross sectional view along the plane of the line 88 in FIGURE 6.

FIGURE 9 is an enlarged, fragmentary, cross sectional view along the plane of the line 9-9 in FIGURE 8.

The banjo-like form of the instrument in FIGURES 1-4 has a generally rectangular frame or body 10 formed of side members 12 connected at their ends by a right or bottom cross member 14, and a left or top cross member 16. A string neck 18 extends from the middle of the top cross member to a peg head 20. The frame members define or surround a generally rectangular opening 22. Adjustable pegs 24 on the peg head tension strings 26 that extend along the neck, and across the opening 22 in the frame to a fixed string anchor 28 on the bottom frame member 14.

Extending across the opening 22 adjacent the top cross member 16 is a rigid, fixed, diaphragm anchor 30- in the form of a strong cylindrical bar having its ends supported in the side members 12. A sheet 32 of flexible material, such as natural animal skin, or a synthetic plastic of suitable strength, is cut to rectangular shape and has one end wrapped around the bar 30 at 34, and wedged in place by the wedge 36. The other end of the sheet 32 is Wrapped at 38 around a hollow cylindrical anchor 40. The anchor 40 is adjustably mounted on pins 42 and 44 secured in the ends of the cylinder, and rotatably mounted in the side members 12. One pin 44 has a worm tooth 46 cut therein within the side member 12, and an adjusting pin 48 extending vertically through the side member has a coacting worm tooth 50 cut therein, so that rotation of pin 48 by a hand piece 52 tightens the diaphragm or sheet 32.

A string bridge 54 is supported by an intermediate portion of the diaphragm, and supports the mid-sections of the strings. With this arrangement of parts, plucking the strings 26 in the manner of playing a banjo produces musical tones closely approximating the tones of a standard banjo. The diaphragm 32 is stretched approximately flush with the top of the frame 10 but. does not touch the frame at any point, except at the anchor 30.

The modified form of instrument shown in FIGURES 59 has a body similar to a common guitar indicated generally at 56. The body has the usual top 58 and bottom 60 defining a resonating chamber with a hole 62 in the top wall. A neck 64 extends from one end of the body to a peg head 66. Strings 68 are stretched by the peg head from a tail piece or anchor 70 on the other end of the body.

The body is varied from a standard guitar by a thin fixed anchor bar 72 secured to the top 58 transversely under the strings. The connection between the anchor bar and the top may be reinforced by an inner backing bar 74 with rivets or other fasteners 76 extending through the bars and the top.

A generally rectangular opening 78 is formed in the top 58 between the fixed anchor 72 and the tail piece 70. Secured to the underside of the top 58 and at each end of the opening 78 are bearing brackets 80 and 82. The brackets may be connected to the backing bar 74 by spacing bars 84. The bars 84 form compression members to carry or resist the tension loads created when the diaphragm is drawn tight, as will be described. An adjustable anchor, in the form of a cylinder 86 for lightness, has pins 88 and 90 connected to its ends. The pins 88 and 90 are received in bearings provided therefor in the brackets 80 and 82 respectively. The pins and bearings are arranged so that the top of the cylinder is approximately level with the top of the fixed anchor bar 72. A rectangular diaphragm 92 of flexible sheet material has one end wrapped around the fixed anchor 72, and its other end wrapped around the cylinder of the adjustable anchor 86 to lie in a plane above the top 58 and below the strings 68. A primary bridge 94 is supported on the diaphragm and supports the strings 68.

In order to tighten the diaphragm 92, the pin 90 has worm thread 96 cut therein which meshes with a worm 3 thread (not shown)'oh' an adjusting pin 98 that projects vertically through the bearing bracket 82 to a finger piece or handle 100. I I

Secured to the top 58 on opposite sides of the diaphragm are a pair of bearings or supports 102 for an auxiliary bridge indicated generally at 104. The auxiliary bridge has concentric ends 106 rotatably journalled in the supports, and an enlarged center portion 108 with a radially enlarged eccentric portion 110 (see FIG. 9). A handle 112 on one end of the shaft permits the auxiliary bridge to be selectively rotated to place eccentric portion in clearing relation to the diaphragm as shown in full lines, or in contacting relation as shown in dotted lines to support the primary bridge directly from the top 58. The circular portion of the enlargement being in constant contact with the top prevents the auxiliary bridge from vibrating when not in use, or other anti-vibration means may be used.

With the auxiliary bridge moved to inoperative position as shown in full lines, the instrument produces a tone similar to that of a banjo, with the resonating effect of the guitar body adding a pleasing modification. With the auxiliary bridge moved to the dotted line position, the ton of the instrument is essentially that of a guitar.

Both forms of the instrument illustrated are examples only and various modifications may be made in the structures thereof without departing from the concept of the invention as defined in the claims. For example, the diaphragm 32 in FIGURE 1 may be stretched transversely with respect to the strings. In the guitar type modification of FIGURE 5, other structure may be provided for stretching the diaphragm between the top 58 and the strings, and other forms of the auxiliary bridge ma be provided. The framework for supporting the fixed anchor and the movable anchor may be located externally of the body, and the diaphragm may be stretched transversely to the strings. In both forms of the instrument, the movable anchor for tightening the diaphragm may be something other than the rotatable cylinders shown.

What is claimed as new is:

1. A stringed musical instrument comprising,

a supporting body having a neck with a peg head at its outer end and a string anchor connected to the body toward the opposite end of the body from the neck,

vibratable strings stretched between said peg head and said string anchor,

a first elongated abutment connected to said body,

a second elongated abutment connected to said body in spaced parallel relation to said first abutment,

a diaphragm of flexible sheet material having its opposite ends connected to said abutments,

means connected to one of said abutments and arranged to adjust the abutment relative to said body to stretch said diaphragm taut,

and a bridge supported on said diaphragm and engaging said strings intermediate of their ends.

2. A stringed musical instrument as defined in claim 1 in which said body is a frame surrounding a generall rectangular opening located under said strings,

said abutments being located adjacent opposite sides of said opening.

3. A stringed musical instrument as defined in claim 2 in which said abutments extend transversely beneath said strings.

4. A stringed musical instrument as defined in claim 2 in which said second abutment is a rotatable member,

and means mounted on said frame connected to rotate the second abutment to tighten said diaphragm.

5. A stringed musical instrument as defined in claim 4 in which said frame has spaced side and end members and is open on the underside opposite said diaphragm.

6. A stringed musical instrument as defined in claim 5 in which said abutments are arranged to stretch said diaphragm longitudinally in a direction parallel to said strings.

7. A stringed musical instrument as defined in claim 1 in which said body ishollow witha resonating cavity and having a top wall with a hole therein located under said strings,

said diaphragm having its center portion positioned in closely spaced relation between said topwall and said strings. I

8. A stringed musical instrument as defined in claim 7 in which said adjustable abutment is secured to the underside of said top wall,'with the upper portion of the abutment projecting through a slot provided therefor in the top wall.

9. A stringed musical instrument as defined in claim 8 in which said adjustable abutment is a roller with the upper portion of its periphery projecting through said 1 slot,

pins projecting from the ends of said roller,

bearings for said pins secured to the underside of said top wall,

and means extending through a wall of said body connected to one of said pins to rotate the roller.

10. A stringed musical instrument as defined in claim 9 in which said means for rotating said roller is a short upright shaft journaled in one of said bearings and having a geared connection to the pin in the bearing, and projecting through said top wall with a driving element on its upper end.

11. A stringed musical instrument as defined in claim 7 in which there are compression members in addition to said body extending between the ends of said abutments.

12. A stringed musical instrument as defined in claim 9 in which said fixed abutment is a bar secured to the top of said top wall,

and compression members connected to said bearings and extending along the bottom of said top wall and gonnected through said top wall to the ends of said 13. A stringed musical instrument as defined in claim 7 in which there is an auxiliary bridge engageable between the top of said top wall and the underside of said diaphragm in the region of the first bridge.

14. A stringed musical instrument as defined in claim 13 in which said auxiliary bridge comprises a shaft journaled in bearings secured to said top wall,

said shaft having an eccentric portion sized to extend between said top wall and said diaphragm, with a portion of lesser diameter sized to clear said diaphragm,

and means connected to said shaft for rotating the same.

15. A stringed musical instrument as defined in claim 14 in which the portion of lesser diameter of said shaft is cylindrical and in constant contact with said top wall.

References Cited UNITED STATES PATENTS 833,517 10/1906 Farmer 84-272 1,642,126 9/1927 Norwood 84-269 RICHARD B. WILKINSON, Primary Examiner JOHN F. GONZALES, Assistant Examiner 

